How can you tell so early?

Sedaya • My name is Sedaya and I'm 23. My husband and I have been together since 2009 and got married April 2015. We have a four year old daughter and had our second daughter 4-16-16 :)
I keep seeing all these women on here between 11-13 weeks pregnant that know the gender! How is this possible. I had my daughter in 2011 and we didn't find out until my 20 week ultrasound. Is there some new stuff being offered? I thought it took that long for a boys parts to develop. I'm currently 12 weeks and I go in for genetic screening this Wednesday. How can I find out?